XII Physics - Past Papers Numericals || Video Lectures

1. 2010 Solved Numericals

Q.2 (viii) A heat engine performing 400 J of work in each cycle has an efficiency of 25%. How much heat is absorbed and rejected in each cycle?

Q.2 (ix) A galvanometer whose resistance is 50  deflects full-scale for a potential diff. 100 mV across its terminals. How can it be converted into a voltmeter of 50V range?

Q.2 (x) Find the current required to produce a field of induction B = 2.512 x 10-3 tesla in a 50 cm long solenoid having 4000 turns of wire. (  = 4π x 10.7 ,wb / A — m)

Q.2 (xi) A water heater that will deliver 1 Kg of water per minute is required. The water is supplied at 20°C and an output temperature of 80°C is desired. What should be the resistance of the heating element in water if the line voltage is 220V? (sp.heat of water = 4200 J/kg.°C)

Q.2(xii) Find the shortest wavelength of photon emitted in to Balmer series determine its energy in eV. (RH= 1.097 x 107m-1)

Q.2(xiii) A deutron (3.3431 x 10-27 Kg) is formed when a proton (1.6724 x 10-27Kg) & a neutron (1.6748 x 10-27 Kg) combine; Calculate the mass defect and binding energy (in MeV)

Q.2(xiv) If the electron beam in a television picture tube is accelerated by 10000 V, what will be the Broglie's wavelength? (h = 6.63 x 10-34 J.s., me = 9.1 x10-31 kg)

Q.2 (xv) How many electrons should be removed from each of two similar spheres each of 10 gm so that electrostatic repulsion may be balanced by gravitational force (e = 1.602 x 10-19 C)?

 

3. 2011 Solved Numericals

Q.2(vi) A 200 gm piece of metal is heated to 150°C and then dropped into an aluminum calorimeter of mass 500 gm, containing 500 gm of water initially at 25°C. Find the final equilibrium temperature of the system if the specific heat of metal is 128.100 J/kg-K, specific heat of aluminum is 903 J/kg-K, while the specific heat of water 4200 J / kg-K.

2. (vii) A particle of mass 1.67 x 10-27 kg and charge 1.6 x 10-19 C is to be held motionless between two horizontal parallel plates, the Voltage applied between the plates is 6 x 10-9 v. Calculate the distance between plates.

2. (viii) An alternating current Generator operating at 50 Hz has a coil of 200 turns, while the coil has an area of 120 cm2. Calculate the magnetic field intensity applied to rotate the coil to produce the maximum voltage of 240 V.

2. (x) A rectangular bar of iron is 2 cm x 2 cm in cross-section and 20 cm long. What is the resistance of the bar at 500°C if =11x 10-8 ohm-m ,  =0.0052 K-1?

2. (xi) Calculate the energy of the longest wavelength radiation emitted in the Paschen series in hydrogen atom spectra. (Rh =1.097 x 10  m-1, h = 6.63 x 10-34 JS, C= 3 x 108m/s)

2. xii) What will be the relative velocity and momentum of a particle whose rest mass is mo, and kinetic energy is equal to twice of its rest mass energy.

2. (xiii) The inner & the outer diameters of the Toroid are 22 cm and 26cm. If a current of 5.0 amp is passed which produces 0.025 tesla flux density inside core, find the approximate length of the wire wound on the toroid.

2 (xv) If the electron beam in a TV picture tube is accelerated by 10 K volt. What will be the de Broglie wavelength of an electron? (h = 6.63 x 10-34 JS, q= 1.6 x 10-19 C, m= 9.11 x 10-31 kg) 


3.  2012 Solved Numericals  

Q.2.(i) You are given three resistors each of 2 ohms. How would you arrange these to obtain equivalent resistance of: (a) 1.33 ohms, (b) 3 ohms and (c) 6 ohms? Verify the results mathematically

Q.2 (ii) Find the current required to produce a magnetic field of induction B = 2.512 x 10-3 web/m in a 50 cm long solenoid having 4000 turns of wire. ( )

Q.2 (iii) A galvanometer of resistance 50 ohms gives full scale deflection with a current of 10 mA. A shunt of 0.05 ohm is connected in parallel to convert it into an ammeter. Find the range of the ammeter.

Q.2 (iv) Given that moc2 = 0.511 MeV. Find the total energy 'E' and the kinetic energy 'k' of an electron moving with a speed V = 0.85c. (e= 9.1 x 10-31 kg, c = 3 x 108 m/s)

 Q.2(x) A Carnot engine whose low temperature reservoir is 200k has an efficiency of 50%. It is desired to increase this to 75%. By how many degrees must the temperature of low temperature reservoir be decreased if the temperature of the higher temperature reservoir remains constant?

Q.2 (xi) Find the value of the shortest and the longest wavelength of emitted photons in hydrogen spectra in Balmer series, where Rh = 1.097 x 107 m-1.

Q.2 (xii) Find the binding energy and the packing fraction in MeV of 52Te126 given that mp = 1.0078u, mn = 1.0086u, mTe = 125.9033u and 1u = 931.5 MeV.

Q.2 (xiii) Two point charges of +2 x 10-4 and -2 x 10-4 coulomb are placed at a distance of 40cm from each other. A charge of +5x 10-5 coulomb is placed midway between them. What is the magnitude and direction of force on it? (K = 9x 109 Nm2/C2)

Q.2(xv) A sodium surface is exposed to a light of wavelength 3 x 10-7 m. If the work function of sodium metal is 2.46 eV, find the K.E. of the photoelectrons and cut off wavelength. ( h = 6.63 x 10-34 J.s, c = 3 x 108 m/s)


4.2013 Solved Numericals

Q.2 (iv) An Alternating current generator operates at 79Hz. The area of the coil is 500cm2. Calculate the number of

turns in the coil when a magnetic field of induction 0.06 web/m2 produces a maximum potential difference of 149

volts.

Q.2 (v) A hydrogen atom in the ground state gets excited by absorbing a photon of 12.15 eV. Find the quantum number

of this state.

Q.2 (vi) Pair annihilation occurred due to a head-on-collision of an electron and a positron having the same kinetic

energy, producing pair of photons each having of 2.5 MeV. What were their kinetic energies before collision? Given

moc2 = 0.511 MeV.

Q. 2(vii) If the number of atoms per gramme of 88Ra226 is 2.66x1021 and it decays with a half life of 1622 years. Find the decay constant and the activity of the sample. (1 year = 3.15 x 107 s)

Q.2 (x) The difference of temperature between a hot and a cold body is 120°C. If the heat engine is 30% efficient, find the temperature of the hot and the cold body.

Q.2 (xi) The surface charge density on a vertical metal plate is 25 x 10-6 c/m2 .Find the force experienced by a charge of 2 x 10 -10 C placed in front close to the sheet.

Q.2 (xii) Two resistors of 5 ohm and 2 ohm are connected in parallel with a 9V battery. Calculate the current and power dissipated in each resistance.

Q.2 (xv) A voltmeter measuring upto 200 volts has a total resistance of 20,000 ohms. What additional series resistance must be connected to it to increase its range to 600 volts?


5. 2014 Solved Numericals

2(i) A galvanometer, having a resistance of 50 ohms deflects full scale for a potential difference of 100 mV across the terminals. What resistance should be connected to increase its range to 50 Volts?

2(ii) A rectangular bar of iron is 2cm x 2 cm in cross section and 20 cm long. What will be its resistance at 500 oC? If α=0.0052 K-1 and ρ = 11 x 10-8ohm m.

2(iii) An iron core solenoid with 500 turns has a cross section of 5 cm2 .A current of 2.3 ampere passing through it produces a flux of  B = 0.53 Telsa. How large an E.m.f is produced in it, if the current is turned off in 0.1 second? What is the self Inductance of the solenoid?

2(iv) What will be the velocity and momentum of a particle whose rest mass is mo and kinetic energy is equal to twice of its rest mass energy?

2 (v) Find the Binding energy and Packing fraction (B.E. per nucleon) of 52Te126. mp = 1.0078u, mn = 1.0086u, mTe =125.9033u and 1u = 931.5 MeV.

2 (vi) Three resistors each of 50 ohm can be connected in four different ways. Find the equivalent resistance for each combination.

2(vii) Calculate root mean square Speed of Oxygen molecule at 800K. Its molar mass is 32 grams and universal Gas constant R = 8.313 J/ mol –K

2(viii) A 10µF is charged to a potential difference of 220V. Its plates are then disconnected from the battery. Its plates are then connected in parallels to another capacitor and it is found that the potential difference falls to 100V.What is the capacitance of the second capacitor?

2(ix) In a TV picture tube, an electron is accelerated by a potential difference of 12000 V. Determine the de Broglie’s wavelength given that h = 6.63 x 10-34 JS, e=1.6 x 10-19 coulomb m= 9.11 x 10-31kg.

2(x) Determine the longest and the shortest wavelength photons emitted in the Lyman series (Rh = 1.097 x 107m-1).


6. 2015 Solved Numerical  

Q.2 iv) What will be the relativistic velocity of a particle whose kinetic energy is twice of its rest mass energy?

 v) Find the Binding energy and Packing fraction (B.E. per nucleon) of 52Te126. mp = 1.0078u, mn = 1.0086u, mTe =125.9033u and 1u = 931.5 MeV.

vi) A heat engine performs 200 J of work in each cycle and has an efficiency of 30 percent. For each cycle of operation, (a) how much heat is absorbed? (b) How much heat is expelled?

vii) A 50 ohm resistor is to be wound from a platinum wire 0.1 mm in diameter. How much wire is needed? (Resistivity of the wire= 11 x 10 -8 Ohm-m)

viii) A galvanometer, whose resistance is 60 ohms, deflects full scale for a potential difference of 100 millivolts across its terminals. What shunt resistance must be connected to convert it into an ammeter of 5 ampere range?

ix) An e.m.f. of 45 millivolts is induced in a coil of 500 turns. When the current in a neighboring coil changes from 15 amps to 4 amps in 0.2 seconds, (a) what is the mutual inductance of the coils? (b) What is the rate of change of flux in the second coil?

x) A thin infinite sheet of uniformly distributed positive charge attracts a light sphere having a charge -5 x 10-6 C with a force of 1.695 N. Calculate the surface charge density of the sheet.

xi) Find the shortest wavelength of photon emitted in the Balmer series and determines its energy in eV. (RH = 1.097 x 107 m-1).

xii) Calculate the speed of the electromagnetic wave, given that,  

xiv) How many electrons should be removed from each of the two similar spheres, each of mass 10 g so that electrostatic repulsion is balanced by the gravitational force? (Gravitational constant = G = 6.67 x 10-11 Nm2 / kg2 and K= 9 x 109 Nm2 /C2) 


7. 2016 Solved Numericals

Q.2 (i) The high temperature reservoir of a Carnot engine is at 200°C and has an efficiency of 35%. To increase the efficiency to 45% by how many degrees should the temperature of cold reservoir be decreased if the temperature of the high temperature reservoir remains constant?

Q.2 (iv) Find the resistance at 100°C of a Silver wire, 1 mm in diameter and 1000 cm long.

Q.2 (v) An iron core solenoid with 600 turns has a cross section area of 2.0 cm2. A current of 4.0 ampere passing through it produces B = 0.4 weber /m2. What emf is produced in it, if the current is turned off in 0.2 second? What is its self-inductance?

Q.2 (vi) Sodium surface is shone with light of wavelength 3x10-7 m. Find the kinetic energy of the emitted photo electrons and the cutoff wavelength of Sodium. Work function of Sodium is 2.46 eV.

Q.2 (vii) Find the shortest and the longest wavelength of emitted photons in Hydrogen spectra in Pfund series.

(viii) The number of atoms per gram of 88Ra226 is 2.666 x 1021 and it decays with a half life of 1622 years. Find the activity and decay constant of the sample.

Q.2 (ix) An α-particle of charge 3.2 x 10-19 C and mass 6.68 x 10-27 kg is held motionless between two Horizontal parallel plates separated by 10 cm. Find the potential difference between the plates.

Q.2 (xi) A proton of charge 1.6 x 10-19 C and mass 1.67 x 10-27 kg is accelerated by a potential difference of 6 x 105 volts. Then it enters perpendicularly into a magnetic field of intensity 0.5 Tesla. Find the radius of the circular path of the proton.

Q.2 (xiv) Find the binding energy and the packing fraction in MeV of 52Te126 given that mp = 1.0078u, mn = 1.0086u, mTe = 125.9033u and 1u = 931.5 MeV.

 

8. 2017 Solved Numericals

 Q.2 (i) A particle of mass 1.67 x 10-27 kg and charge 1.6 x 10-19 C is to be held motionless between two horizontal parallel plates, the Voltage applied between the plates is 14.32 x 10-9 v. Calculate the distance between plates.

Q.2 (iii) Calculate the temperature at which the root mean square speed of hydrogen molecules is 3300 m/s. Give your answer in degree Celsius (m = 3.32 x 10-27 kg).

Q.2 (v) A 400 volts voltmeter has a total resistance of 40000 ohms. What additional series resistance must be connected to it to increase its range to 750 volts?

Q.2 (vi) X-rays of wavelength 3.64 x 10-10 m are used in Compton scattering process. Find the fractional change in wavelength for a scattering angle of 120°. (Give h = 6.63x10-34Js, m0=9.1x10-31kg, c = 3 x108m/ s)

Q.2 (vii) The half life of 104Po210 is 140 days. By what percent will its activity decrease per hour?

Q.2 (viii) How much energy is needed to ionize a hydrogen atom originally in ground state? 6.63 x 10-34Js, c = 3 x 108m/ s, RH =1.097 x 107 m-1)

Q.2 (x) An alternating current generator operates at 79 Hz. The area of the coil is 500 cm2. Calculate the number of turns in the coil when a magnetic field induction 0.06 tesla produces a maximum potential difference of 149 volts.

Q.2 (xi) A deuteron of mass 3.3431 x 10-27 kg is formed when a proton of mass 1.6724 x 10-27 kg and a neutron of mass 1.6748 x 10-27 kg combine. Calculate the mass defect and binding energy In MeV.

Q.2 (xii) The resistance of a platinum resistance thermometer is 200 ohms at 0°C and 257.6 ohms when immersed in a hot bath. What is the temperature of the bath (α= 0.00392 0C-1 )


9. 2018 Solved Numericals  

2(ii) Find the potential difference at the ends of 15 m long copper wire 0.5 mm in diameter to maintain a steady current of 4 A.( Resistivity of Copper = )

2(iv) Find the Q-value of the reaction 92Pu239 à2He4 + 92U235 +Q

The isotopic mass of plutonium = 239.0522 u   The isotopic mass of uranium = 235.0439 u

The isotopic mass of alpha particle = 4.0026 u 1 u => 931.5 MeV

2(vi) A system absorbs 1147 joules of heat, loses 233 joules of heat by conduction to the surroundings and delivers 614 joules of work. Calculate the change in internal energy of the system.

2(viii) A photon of what minimum energy is required to excite a hydrogen atom from n=1 to n=3?    (Rh= 1.097 x 107 m-1).

2(x) Two unequal point charges repel each other by a force of 10 N when they are 10 cm apart. Find the force which they exert on each other when they are 1 cm apart. If the magnitude of one point charge is . Find the magnitude of the other.

2(xii) A current of 6.25 A is maintained in a long straight conductor by a source. Calculate the force per meter on a similar parallel conductor in air at a distance of 0.5 m from the first and carrying a current of 2 A.

2(xiv) A photon of wavelength 0.004 A0 in the vicinity of a heavy nucleus produces an electron positron pair. Find the kinetic energy of each particle in MeV, is the kinetic energy of positron is twice that of electron.

 

10.  2019 Solved Numericals

Q.2 (ii) If the number of atoms per gramme of 88Ra226 is 2.66x1021 and it decays with a half life of 1622 years. Find the decay constant and the activity of the sample. (1 year = 3.15 x 107 s)

(iii) A coil of 400 turns in an AC generator having an area of 0.1 m2 is rotating in a magnetic field of 50 T.In order to generate a maximum voltage of 220 volts, how fast is the coil to be rotated? Express your answer in revolutions per second.

(vi) What is the wavelength of 3rd spectral line of Paschen series in hydrogen atom? (Rh= 1.097 x 107 m-1).

(viii) A rectangular bar of iron is 2cm x 2cm is cross section and 20 cm long. What will be its resistance at 5000C? (α=0.0052 K-1 and ρ=11 x 108 ohm-m)

(ix) Two capacitors of 2µF and 4µF are connected in series to a 40 volt battery. Calculate the charge on these capacitors and potential difference across each.

(x) Find the change in volume of an aluminium sphere of 0.4 m radius when it is heated from 0 to 100o C. (α=24 x 10-8 0C-1)

(xv) What will be the velocity and momentum of a particle whose rest mass is mo and kinetic energy is equal to twice of its rest mass energy?

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